Preheat oven to 350 degrees F (175 degrees C). Arrange pecans on a single layer on a baking sheet and roast in preheated oven for 7-10 minutes, until they just begin to darken. Remove from oven and set aside.
Peel peaches (if desired) and slice into bite-sized segments. Combine peaches, spinach and pecans in a large bowl. Toss with dressing until evenly coated, adding a little additional dressing, if necessary.